Gardening Question of the Day

Why do some leaves on my rhododendron have brown spots?

Random brown spots on older leaves are likely caused by a fungus. Unless widespread, they are not a cause for concern. Some cultivars or hybrids are resistant. Try the cultivars 'Solidarity', 'Caroline', and 'Mardi Gras', as well as the species hyperythrum, yakushimanum or degronianum.

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How do you care for a mistletoe cactus?

The mistletoe cactus, unlike its other cactus relatives, needs an indoor environment that is very humid--60 percent humidity is best. It also requires bright, filtered light.

Can one grow holly in northern climes?

Yes, but this hasn't always been the case. Prolonged exposure to cold and winter winds made growing holly impossible where winters can be harsh. But, in the mid-1960s Meserve or "Blue" hollies were introduced. These are a cross between English holly and the extremely hardy prostrate holly. The Meserves will grow as far north as USDA Zone 4.

Can I use my Christmas tree for mulch after Christmas?

Yes. Remove the branches and chop the trunk for use as mulch.

I have a healthy gardenia in a pot. The plant is well over a year old and has yet to bear flowers. Any ideas as to why?

Gardenias are very sensitive to temperature changes. They prefer 70 degrees F during the day and 60 to 65 degrees F at night. Nights above 65 degrees F will reduce bud growth and increase the chances of buds dropping off. Gardenias like high humidity and bright light. Keep the soil moderately moist at all times.

Will asters survive the winter in northern Kentucky? What measures should I take to ensure this?

Asters will generally do nicely in a Kentucky winter. Mulching does provide protection, and we recommend it. It's good for preventing soil crusting, conserving moisture, and controlling weeds. Don't go too heavy, though. This can result in too much moisture retention and crown rot. Pine bark, pine straw, wood chips, and a variety of other materials may be used successfully.

Should I mulch my perennials for the winter?

Yes, you should do this once your ground is frozen hard.

What is the best way to get rid of thistles?

The thistle is one of the most difficult perennial weeds to control because its underground stems can travel up to 20 feet a season. After chopping them down, use a plastic mulch to cover the entire area. A straw mulch, laid at least three inches thick, also will smother thistles. (Do not use a leaf mulch.) Your weed-control program must be long-lasting because the roots can lie dormant for several years. In addition to mulching, plowing the garden deeply in the fall will bring the rhizomes (stems) to the surface. But avoid rototilling, because this will cut the rhizomes, and each piece will become a new plant.

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